A variety of coloring materials is used for image printing. One of the coloring materials includes a high-functioning toner, which is different from a conventional toner of YMCK colors. For example, one of the high-functioning toner is a toner containing bright (glittering) pigment particles, which delivers metallic luster or pearl luster as a colorant.
A particle diameter of conventional bright pigment particles is evenly large and the particle diameter thereof is approximately from 1 μm to 500 μm. In addition, the bright pigment includes a flat reflecting surface with which light reflects in a complicated manner. In general, as the particle diameter becomes large, the number of the reflecting surfaces increases and strong metallic luster or pearl luster can be obtained. Meanwhile, when the particle diameter of the bright pigment is small, it is difficult to obtain the metallic luster or pearl luster.
When the bright pigment is used for an image, viewers of the image may recognize that the image has a brilliant gloss because the viewers recognize scattering light reflected on the image. To reflect the light, it is necessary to align the reflecting surfaces of the bright pigment particles to be substantially parallel to an image surface.
One of the bright pigment particles includes a base portion and metal oxide (titanium oxide or iron oxide) coated on the surface thereof. For the base portion, mica or the like having a chemically high stability and excellent heat resistance may be used. The pearl luster is obtained by coating the surface of the base portion with metal oxide having a different refractive index from that of the base portion.
However, the toner containing the glittering pigment particles is less likely to retain a sufficient amount of electric charges required for image forming or tends to be susceptible to an environmental change. Therefore, a toner containing the glittering pigment particles that enables a more reliable image forming is demanded.